Type CO Overcurrent Relay
41-101U
15
A core screw accessible from the top of the switch
provides the adjustable pickup range.
3.0
CHARACTERISTICS
The relays are generally available in the following
current ranges.
These relays may have either single or double circuit
closing contacts for tripping either one or two circuit
breakers.
The time vs. current characteristics are shown in Fig-
ures 7 to 13. These characteristics give the contact
closing time for the various time dial settings when
the indicted multiples of tap value current are applied
to the relay.
3.1
TRIP CIRCUIT
The main contacts will close 30 amperes at 250 volts
dc and the seal-in contacts of the indicating contac-
tor switch will carry this current long enough to trip a
circuit breaker.
The indicating instantaneous trip contacts will close
30 amperes at 250 volts dc, and will carry this cur-
rent long enough to trip a breaker.
The indicating contactor switch has two taps that
provide a pickup setting of 0.2 to 2 amperes. To
change taps requires connecting the lead located in
front of the tap block to the desired setting by means
of a screw connection.
3.2
TRIP CIRCUIT CONSTANTS
Contactor Switch -
0.2 ampere tap = 6.5 ohms dc resistance
2.0 ampere tap = 0.15 ohms dc resistance
4.0
SETTINGS
CAUTION
!
Since the tap block screw on both the CO unit
and IIT unit carries operating current, be sure
that the screws are turned tight.
In order to avoid opening current transformer
circuits when changing taps under load, the re-
lay must be first removed from the case. Chassis
operating shorting switches on the case will short the
secondary of the current transformer. The taps
should then be changed with the relay outside of the
case and then re-inserted into the case.
Range
Taps
†
.1 - .5
0.1
0.12 0.16 0.2
0.3
0.4
0.5
.5 - 2.5
0.5
0.6
0.8
1.0
1.5
2.0
2.5
2.0 - 6.0
2.0
2.5
3.0
3.5
4.0
5.0
6.0
4.0 - 12.0 4.0
5.0
6.0
7.0
8.0 10.0 12.0
†
Available for Type CO-11 Relay Only.
Figure 14: Internal Schematic of the Double Trip Circuit
Closing Relay. For the Single Trip Relay the
Circuits Associated with Terminal 2 are Omit-
ted.
Figure 15: Internal Schematic of the Single Trip Circuit-
Closing Relay with Indicating Instantaneous
Trip Unit.
Sub 3
57D4524
Sub 7
57D4525
Summary of Contents for 41-101U
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